Abrasive articles have been utilized to abrade and finish workpiece surfaces for well over a hundred years. These applications have ranged from high stock removal, high pressure metal grinding processes to fine polishing, such as of ophthalmic lenses. In general, abrasive articles are made of a plurality of abrasive particles bonded either together (e.g., a bonded abrasive or grinding wheel) or to a backing (e.g., a coated abrasive). For a coated abrasive there is typically a single layer, or sometimes two layers, of abrasive particles. Once these abrasive particles are worn, the coated abrasive is essentially worn out and is typically discarded.
A more recent development in three-dimensional coatings of abrasive particles has provided abrasive articles often referred to as “structured abrasives”. Various constructions of structured abrasive articles are disclosed, for example, in U.S. Pat. No. 5,152,917 (Pieper et al.), which is herein incorporated by reference. Pieper teaches a structured abrasive that results in a relatively high rate of cut and a relatively fine surface finish on the workpiece surface. The structured abrasive comprises non-random, precisely shaped abrasive composites that are bonded to a backing.
Other references directed to structured abrasive articles and methods of making them include U.S. Pat. No. 5,855,632 (Stoetzel et al.), U.S. Pat. No. 5,681,217 (Hoopman et al.), U.S. Pat. No. 5,435,816 (Spurgeon et al.), U.S. Pat. No. 5,378,251 (Culler et al.), U.S. Pat. No. 5,304,223 (Pieper et al.), and U.S. Pat. No. 5,014,468 (Ravipati et al.), all of which are herein incorporated by reference.
Pieper, and the other structured abrasive patents, are a significant advancement in the abrasives art, however there is always room for improvement.